Turbochargers produce aerodynamic noises that can annoy vehicle passengers as well as those in the surrounding environment. Such noises can propagate to other engine system components where acoustic energy may be detrimental and increase wear. In general, most people view turbocharger noise as a nuisance.
For a properly operating, conventional turbocharger, the intake air compressor and the exhaust turbine generate noise. Characteristics of generated noise typically change with operating conditions. For example, as a compressor moves toward surge (a non-optimal operating condition), noise generation can intensify due to flow separation at the suction side of the compressor blades. This noise can propagate through the high density compressed air as well as through structures connected to the compressor.
While turbocharger noise can lead to complaints, noise can also provide information as to particular issues associated with turbocharging (e.g., compressor wheel imbalance, etc.). However, upon inspection, most noise complaints are determined to be associated with normal turbocharger operation. Thus, techniques that reduce turbocharger noise have the potential to reduce not only complaints but also unwarranted service calls.